the problem about go into low power mode

[Beike]

board: custom board nrf52840

IDE:                          keil5

SoftDevices:             s140 V6.0.0

SDK:                        15.0.0

hi, I want to decrease my consumption of my board.

Now, i enable the SoftDevices and call sd_app_evt_wait(), the consumption is 12.4 uA. but from the 52840 manual we can know that the consumption should be 1.3 uA in on mode without ram retention.

and then, I close ram retention by call "ret_code = sd_power_ram_power_clr(i, 0x00030003);" , but it's no effect, the consumtion still is 12.4 uA. 

by debug mode, I get the "ret_code" is not "NRF_SUCCESS", it's 2. can anyone tell me what this ret_code = 2 means? or how to decrease consumption to 1.3 uA?

this is my code:

u32 ret_code = 0;
void pwr_init()
{
	int i;
	
	for(i=0; i<8; i++)
	{
		ret_code = sd_power_ram_power_clr(i, 0x0UL);
		ret_code = sd_power_ram_power_clr(i, 0x00030003);
	}
	ret_code = sd_power_ram_power_clr(8, 0x0UL);
	ret_code = sd_power_ram_power_clr(8, 0x003f003f); 
	// I don't want to recover anthing from low power mode, it's will reset
}

int main(void)
{
	pwr_init();
	dev_init();
	ble_stack_init(); // a custome function, it will enable softdevice.
	for (;;)
	{
    	sd_app_evt_wait();
	}
}

[AndreasF]

Hi Beike.

If you use APP_ERROR_CHECK() on your ret_code you can find out that this error is found in nrf_error.h on line 63.

#define NRF_ERROR_SOFTDEVICE_NOT_ENABLED      (NRF_ERROR_BASE_NUM + 2)  ///< SoftDevice has not been enabled

This is because you use the pwr_init(); function before you enable the SoftDevice in the ble_stack_init(); function.

- Andreas

[Beike]

Hi Andreas. thanks for your answer.

I will test this tomorrow, cal pwr_init() after call ble_stack_init().

by the way, I use NRF_POWER->RAM[i].POWERCLR = 0x00030003 in stead of  sd_power_ram_power_clr before call ble_stack_init(),  it result the code jump into HardFault handler function and  cant't download to 52840 anymore.

can you tell me why?

[AndreasF]

Hi Beike.

Using NRF_POWER->RAM[i].POWERCLR = 0x00030003 before you call ble_stack_init() should work fine.

Are you sure you did not use it after you call ble_stack_init(), because that does not work.

- Andreas